1. Field of the Invention
The present invention relates to a grinder capable of performing the operations ranging from rough grinding to mirror-like finishing of the elongate peripheral surface of a work rotated around the central longitudinal axis thereof.
2. Description of the Prior Art
For attaining a mirror-like finish of the outer periphery of a work in the form of a round shaft, for example, a roller, round column, cone, or cylinder, the work must be ground in turn by grindstones in a plurality different from each other in grain size and adaptable to processes ranging from rough grinding to mirror-like finishing.
Mirror-like finishing of the work as described above is carried out in such steps that a rotating grindstone is brought into contact with the peripheral surface of a work to be ground and the grindstone is shifted along the longitudinal direction of the central axis of the work while contact as described above is maintained, such steps being preferable with respect to efficiency and accuracy.
Conventional type grinders employing a grinding method as described above have a structure in which a revolving shaft, having a grindstone fixed to the tip of the swing arm thereof to swing around a fulcrum, is supported by bearings to be exerted by the grindstone on the work is determined by a sliding weight to be stopped at a fixed position on the tip portion of the swing arm so that the grinding operation capable of following the oscillation or eccentricity of the work may be possible.
However, since grindstones adaptable to operations ranging from rough grinding to mirror-like finishing are different from each other in grain size, the following procedures are required for replacement thereof: first, releasing contact thereof with the work, stopping the grinder, pushing up the tip of the swing arm, removing the grindstone from the rotating shaft, fixing another grindstone to the rotating shaft, driving the grinder again, and determining a degree of pressing force of the grindstone against the work.
Consequently, a long period of time and many hands are required for replacement of grindstones, also, the grinder is inevitably stopped during this period, thereby causing low operation efficiency and high operation cost.
Particularly, a series of operations ranging from rough grinding to mirror-like finishing require more than three kinds of grindstones and, therefore, replacement of grindstones is a cause of low operation efficiency.